HER2-positive cancers have too many copies of the HER2/neu gene, which make too much of the HER2 protein. The HER2 protein sits on the surface of cancer cells and receives signals that encourage the cancer to grow and spread. About one out of every four breast cancers is HER2-positive.

Like Herceptin (chemical name: trastuzumab), Tykerb works against cancers that are HER2-positive. Tykerb works by blocking the HER2 protein’s ability inside the cell to make HER2-positive breast cancers grow. Tykerb is approved by the U.S. Food and Drug Administration (FDA):

to be given in combination with Xeloda (chemical name: capecitabine), a type of chemotherapy, to treat HER2-positive, metastatic breast cancer that has stopped responding to anthracyclines, taxanes, and Herceptin

to be given in combination with Femara (chemical name: letrozole), a type of hormonal therapy, to treat postmenopausal women diagnosed with hormone-receptor-positive, HER2-positive, metastatic breast cancer.

Doctors can choose to use Tykerb to treat other stages of breast cancer whether or not that particular use is officially approved by the FDA. Tykerb is a pill taken by mouth.

Taxol, a taxane chemotherapy, works by interfering with the ability of cancer cells to divide. Taxol usually is given in combination with other medicines and is used after surgery to:

reduce the risk of early-stage breast cancer coming back

treat advanced-stage breast cancer after it stops responding to standard chemotherapy therapy regimens that include an anthracycline

Taxol is given intravenously.

In this study, the researchers wanted to know if combining Tykerb with Taxol could safely offer more benefits than Taxol alone to treat newly diagnosed HER2-positive, metastatic breast cancer.

Half of 444 women newly diagnosed with HER2-positive, metastatic breast cancer were randomly assigned to receive Taxol plus Tykerb. The other half of the women received Taxol plus a placebo (a sugar pill that looked just like Tykerb). Neither the doctors nor the women knew who was getting Tykerb and who was getting the placebo.

The women who got Taxol plus Tykerb had better overall survival, living about 7 months longer compared to the women who got only Taxol (27.8 months versus 20.5 months). Overall survival is how long the women lived, whether or not the cancer grew.

The women who got Taxol plus Tykerb also had better progression-free survival (9.7 months versus 6.5 months) compared to women who got only Taxol. Progression-free survival is how long the women lived without the cancer growing.

Overall, 69% of the women had some sort of response to the Taxol-Tykerb combination compared to 50% of the women who had a response to Taxol.

The most common side effects of Tykerb are diarrhea, redness and tingling in the hands and feet, and a rash. These side effects usually aren’t severe. Other side effects can include stomach upset, vomiting, and fatigue. Tykerb costs $5,000 to $6,000 per month.

The most common side effects of Taxol are a low white blood cell count, allergic reactions, hair loss, numbness in the fingers and toes (neuropathy), diarrhea, vomiting, and mouth sores.

In this study, the most common side effects were diarrhea, low white blood cell count, and rash. These side effects happened more often and were more severe in the women who got the Taxol-Tykerb combination. About 13% of women (29 women) who got the Taxol-Tykerb combination had to stop taking the medicines because of side effects.

If you’re newly diagnosed with HER2-positive, metastatic breast cancer, you and your doctor will consider a number of treatment options. It’s important to remember that while there are many standard regimens, each person’s treatment plan will be unique because each cancer is unique. Besides the characteristics of the cancer, your doctor also will take into account other health issues you may have, including heart problems, high blood pressure, and diabetes. These and other conditions can affect which medicines your doctor recommends for you. If your doctor recommends Taxol alone, you may want to mention this study and ask if adding Tykerb to Taxol would offer benefits for you and your unique situation.

For more information on Tykerb, visit the Breastcancer.org Targeted Therapies pages. For more information on Taxol, visit the Breastcancer.org Chemotherapy pages.